Comment on the method and quality of the instructor's teaching. Be specific about strengths, weaknesses, teaching techniques, congeniality of the learning environment and any suggestions for improvement.
I really didn't attend enough classes to make any sort of good comments. I was pretty bored though the first few weeks when I attended.
The guest speaker from Google was good, but had I known it was a guest speaker I would have skipped.
Also, when filling out course evaluations, why do so many people not think about how they're displayed? By this point you have to know that the responses get grouped by question, not by student. So stop putting "see above" or "like I said above" or "the aforementioned" because nobody knows what you're talking about. Just answer each question in the right box. There are certainly tougher things in law school.